Sometimes, you may have one or more derived files
already built in your local build tree
that you wish to make available to other people doing builds.
For example, you may find it more effective to perform
integration builds with the cache disabled
(per the previous section)
and only populate the shared cache directory
with the built files after the integration build
has completed successfully.
This way, the cache will only get filled up
with derived files that are part of a complete, successful build
not with files that might be later overwritten
while you debug integration problems.

In this case, you can use the
the --cache-force option
to tell SCons to put all derived files in the cache,
even if the files already exist in your local tree
from having been built by a previous invocation:

Notice how the above sample run
demonstrates that the --cache-disable
option avoids putting the built
hello.o
and
hello files in the cache,
but after using the --cache-force option,
the files have been put in the cache
for the next invocation to retrieve.